The present invention relates to a frame- or bracket-shaped auxiliary handle for a handheld machine tool, in particular a chiseling handheld machine tool.
Frame-shaped auxiliary handles are used on heavy, powerful, chiseling handheld machine tools. Users can guide and lift the handheld machine tool by means of the auxiliary handle. U.S. Pat. No. 7,823,256 discloses an auxiliary handle having a frame-shaped grip. A clip may enclose a neck of a hammer drill. A clamping lever tightens the clip to secure the auxiliary handle to the neck.
Vibrations of the handheld machine tool are transmitted to the auxiliary handle. The auxiliary handle is intended to dampen the vibrations in addition to having good control characteristics.
The auxiliary handle, according to the invention, has a frame-shaped handle which has a grip bar for gripping by a user, a crossbar and two flanks connecting the grip bar to the crossbar. Fastened to the crossbar is a loop-shaped clamping element for attaching to a neck of the handheld machine tool. A clamping mechanism serves to clamp the clamping element around the neck of the handheld machine tool. The frame-shaped handle has a frame-shaped base body of a first injection-molded plastic, the body having a solid body joint in the region of each of the flanks. A casing made of a second plastic surrounds the frame-shaped base body in the region of the grip bar and the flanks.
The two solid body joints support the grip bar against undesired tipping movements and still allow a damping along the most highly loaded direction, namely the work axis of the handheld machine tool.
The solid body joints may be formed by a constriction of the base body along a direction perpendicular to a plane stretched from the grip bar and the crossbar. The constriction is preferably perpendicular to a plane stretched from the frame-shaped grip. A dimension of the base body perpendicular to a plane stretched from the grip bar and the crossbar in the region of the solid body joint may be 10 to 25% of the dimension of the base body perpendicular to the plane in the region of the grip bar. The stiffness of the grip bar is correspondingly several times greater along the direction.
The solid body joints may be designed in a wavy manner to obtain a damping during a movement of the grip bar in a direction toward the grip bar.
The auxiliary handle may be characterized in that the solid body joints are fully filled with the first plastic and the second plastic in a plane perpendicular to the pivot axis, wherein a proportion of the first plastic lies between 10% and 20%. In the pivot direction, the solid body joint consists preferably primarily of a softer plastic. The grip may have in the region of the solid body joints a circular or elliptical cross-section with a maximum difference between the large semi-axis to the smaller semi-axis of 10%, wherein the cross-section is completely filled by the base body and the second synthetic material.
The following description explains the invention by means of illustrative embodiments and drawings.